1. Field of the Invention
This invention pertains to an implant for passing blood flow directly between a chamber of the heart and a coronary vessel. More particularly, this invention pertains to an insertion tool to facilitate insertion of such an implant into the coronary vessel.
2. Description of the Prior Art
U.S. Pat. No. 5,755,682 dated May 26, 1998 and PCT Application No. PCT/US97/13980 (International Publication No. WO 98/06356 based U.S. Pat. application Ser. No. 08/882,397 filed Jun. 25, 1997) teach an implant for defining a blood flow conduit directly from a chamber of the heart to a lumen of a coronary vessel. An embodiment disclosed in the aforementioned patent and applications teaches an L-shaped implant in the form of a rigid conduit. The conduit has one leg sized to be received within a lumen of a coronary artery and a second leg sized to pass through the myocardium and extend into the left ventricle of the heart. As disclosed in the above-referenced patent and applications, the conduit is rigid and remains open for blood flow to pass through the conduit during both systole and diastole. The conduit penetrates into the left ventricle in order to prevent tissue growth and occlusions over an opening of the conduit.
Commonly assigned and co-pending U.S. Pat. application Ser. No. 08/944,313 filed Oct. 6, 1997, entitled xe2x80x9cTransmyocardial Implantxe2x80x9d teaches an implant such as that shown in the aforementioned ""682 patent with an enhanced fixation structure. The enhanced fixation structure includes a fabric surrounding at least a portion of the conduit to facilitate tissue growth on the exterior of the implant.
Implants such as those shown in the aforementioned applications include a portion to be placed within a coronary vessel and a portion to be placed within the myocardium. When placing a portion of the implant in the coronary vessel, the vessel is axially incised a length sufficient to insert the implant. Such an incision results in a contraction of the coronary vessel to a size substantially smaller than the implant. Therefore, it is difficult to insert the implant into the lumen of the coronary vessel. Such vessels are elastic and can be urged to an expanded shape sufficient to fit over the implant. However, due to the small size of the vessel, restricted space for manipulating surgical tools, and the importance of avoiding damage to the coronary vessel, such a manipulation of the vessel is difficult.
According to a preferred embodiment of the present invention, an insertion tool is disclosed for facilitating insertion of a vessel end of a transmyocardial implant into a coronary vessel. The transmyocardial implant has a hollow conduit for establishing a blood flow path through a myocardium between a heart chamber and a lumen of a coronary vasculature residing on an exterior of said wall. The vessel end has an external geometry for the vessel end to be received within the lumen. The vessel end has a generally tubular external geometry and an axial opening at a leading end. The coronary vessel has a constricted size and is expandable to a larger expanded size. The insertion tool includes a sheath having an external dimension sized for the sheath to be received within the lumen of the expanded size of the coronary vessel. A dilator is removably inserted through the sheath. A leading end of the dilator is sized to be received within the lumen of the constricted size of the coronary vessel. The dilator is removed from the sheath after placement of the dilator and sheath in the vessel. The implant is then placed in the sheath. The sheath is retracted from the vessel without disrupting the coronary vessel.